1. Field of the Invention
The present invention generally relates to a lens module, and more particularly, to a miniaturized lens module capable of continuous focusing with different focus lengths.
2. Description of Related Art
Along with the progress of the communication industry, mobile phones have been broadly used by the people. Nowadays, a person owns one or more mobile phones; even children or seniors use the mobile phone for communicating with relatives. Accordingly, a great demand on handsets is obvious and is progressively growing. As a consequence, the handset market is overwhelmingly growing.
Along with the development of the multimedia technology, more and more handsets with additional functions, such as photographing function and video-graphing function, are now become general requisite functions of a handset. To meet the present compactness, flatness and thinness trend, the optical system and actuator of a built-in camera has to be designed as simple and compact as possible.
Accordingly, the camera module in a handset is limited to have the auto-focusing and zooming in steps functions only. For example, the lenses of the lens module in some handsets are driven by a cam, wherein an auto-focusing is available at the wide-end and the tele-end thereof. During a continuous zooming, for example, from the wide-end to the tele-end, there is no auto-focusing function for an intermediate zoom magnification at all.
In order to realize continuous zooming, i.e. auto-focusing function covering different focal lengths, the tracks of the above-mentioned cam must have a complex structure, which would increase the cam diameter, and therefore it would difficult achieved present trend of miniaturization.
The Korean Patents KR 10-0526652 and KR 10-0542074 disclose such a zooming scheme using a motor to indirectly or directly drive a barrel cam with groove tracks. According to the Korean patents however, it is difficult to have an auto-focusing function, unless the auto-focusing function is provided at the wide-end or tele-end thereof only by designing the groove tracks of the barrel cam. But the scheme is difficult to realize the auto-focusing covering all different focus length sections.